Yarn entanglement tester

ABSTRACT

A yarn entanglement tester using a needle placed in intermingling obstruction of a traveling yarn. The intermingling of the filaments in the yarn is detected by the needle point penetrating the yarn and as the needle is deflected through engagement of an entanglement, it makes a contact closure completing a resistive circuit which in turn activates a solenoid coil to retract its core, which carries the needle, thus removing the needle from the yarn. Simultaneously, a count is made on a totalizing counter and once the circuit is opened by the needle being fully retracted, a spring action reinserts the needle into the fiber. The operational cycle of the detector is on the order of milliseconds. The tester is composed of two main units; a control display and testing assembly and a control unit assembly containing counting circuit control relays.

United States Patent Goldfarb et al.

[ Feb. 26, 1974 Primary ExaminerRichard C. Queisser Assistant ExaminerDenis E. Corr [57] ABSTRACT A yarn entanglement tester using a needle placed in intermingling obstruction of a traveling yarn. The intermingling of the filaments in the yarn is detected by the needle point penetrating the yarn and as the needle is deflected through engagement of an entanglement, it makes a contact closure completing a resistive circuit which in turn activates a solenoid coil to retract its core, which carries the needle, thus removing the needle from the yarn. Simultaneously, a count is made on a totalizing counter and once the circuit is opened by the needle being fully retracted, a spring action reinserts the needle into the fiber. The operational cycle of the detector is on the order of milliseconds. The tester is composed of two main units; a control display and testing assembly and a control unit assembly containing counting circuit control relays.

5 Claims, 5 Drawing Figures PATENTEB FEBZ 6 I974 SHEEI 2 [1F 5 Om NON mmwe lT oQ @Q N:

YARN ENTANGLEMENT TESTER This invention relates to a yarn entanglement tester. Entangled yarn is where individual filaments and groups of filaments are randomly interrnigled with adjacent filaments along the length of the yarn.

Prior evaluation procedures have been complicated and failed to give an accurate indication of the entanglement factor of a given yarn. A commonly used concept in the past has been to take 100 cm. length of yarn and vertically tension it with 100 gms., assuming that the total yarn denier is greater than 500. A hook weighing gms. is usually inserted into the yarn and descends at the rate of 1 to 2 centimeters per second until the hook is supported by the yarn. The hook traverse is measured and recorded. Approximately one hundred determinations are made for each yarn sample. The highest and lowest twenty percent of the data is discarded and the remainder are averaged. The average hook drop distance is divided into hundredths to yield a coherency factor, the absolute value of which is the index of the degree of entanglement. In some cases, it has been preferable to simply report the hook drop distance which is in inverse proportion to the degree of entanglement.

Existing instruments adaptable to this procedure use a crosshead which provides a convenient vehicle to lower a hook at 1 to 2 centimeters per second. This instrument usually can accommodate approximately 10 yarns per crosshead descent.

The problems of the existing manual and machine procedures are many. Initially they require a considerable amount of operator time and also involve considerable judgement in making determinations. In other words, they have to make an estimation up to one millimeter of a meter stick. Furthermore, the prior procedures required considerable replication and involved considerable operator variation.

The instant yarn tester obviates all of the foregoing disadvantages and problems. It measures a minimum of 10 times the number of entanglements previously measured, thereby vastly improving accuracy and also reducing analysis costs since the measurement is made in one-tenth of the time.

The intermingling of the filaments in the yarn is detected by a needlepoint penetrating the yarn in the instant invention. As the needle is deflected through engagement of an intermingling obstruction, it makes a contact closure completing a resistive circuit. This momentarily deactivates a solenoid which in turn permits a spring to retract the core carrying the needle point, thus removing the needle point from the fiber. Simultaneously, a count is made on a totalizing counter. once the circuit is opened by the needle being fully retracted, the solenoid is activated to reinsert the needle into the fiber. The operational cycle of the detector is in the order of milliseconds. This frequency is capable of detecting the entanglements on samples of yarn representing the highest level of filament intermingling. The needle is designed to be calibrated to make contact when the force of the obstruction is ten grams or if it is desired, some lesser or greater value.

A timing circuit automatically controls the duration of the test period and also controls the drive and counting systems. The yarn is designed to move past the needle at a constant velocity of l centimeter per second with a regulated tension on the yarn of 100 grams.

The instant system tests five strands of yarn simultaneously. The tester can be loaded from a cart containing a number of bobbins and fed past a detector and through nib rolls into a receiving container. The fiber is constrained in a groove while passing the detector area and the nib rolls pull the fiber at a constant rate.

Activation of the system starts the movement of the fiber and the delay timer. Once the delay time has passed, the test timer commences and the count accumulates. At the conclusion of the times test period, which is adjustable, the system is stopped and the needle locked in a position free from the path of fiber travel. The operator then records the number of entanglements recorded from each strand of yarn, cuts the strand and prepares for the next series of tests.

Accordingly, it is an object of this invention to provide a yarn entanglement tester which overcomes all of the above described disadvantages and operates in a highly efficient and fast manner. It is a further object of this invention to provide a yarn entanglement tester whereby a solenoid actuated needle point is inserted into traveling yarn for a given period of time. A further object of this invention is to provide a yarn entanglement tester using counter circuits and relay circuits to insert a needle into a traveling length of yarn and to retract it for a given time period upon it encountering an obstruction within the yarn.

It is a further object of this invention to provide an automatic yarn entanglement tester which enables an operator to test approximately ten times the present capacity of the above manual and automatic methods.

A still further object of this invention is to provide a yarn entanglement tester which can handle from 800 denier yarns to 4,000 denier yarns.

These and other objects of the invention will become apparent in the accompanying specification when taken with relation to the accompanying drawings in which:

FIG. 1 is a perspective view of the overall machines showing the control display panel and the detection apparatus;

FIG. 2 is a diagrammatic view of the yarn attesting groove, the adjustment mechanism, and the needle insertion retraction assembly;

FIGS. 3a, 3b and 30 comprise an electrical schematic of the various relays and operative components of the control system.

Referring now to FIG. 1, the apparatus is shown generally designated as 2. It consists of a front vertical panel 4 and a display panel 5. Display panel 5 is a series of operational buttons, namely the ON button 6, the calibration or CAL button 8, the LACE button 10, the RUN button 12, the STOP button 14, and the OFF button 16. A series of counters are located on the display panel and are indicated as 20, 26, 28, 30 and 32. Each counter has an indicator light such as 24 and a mechanical counter such as 22. Located under the OFF button are a series of fuses such as 18.

A main base portion 34 extends from panel 4 outwardly therefrom and has a bracket 38 on one side and a planar surface member 36 on the other side thereof. A series of pretensioners such as 40, 52, 54, 56 and 58 are located on planar portion 36. The pretensioners control tension discs, such as 46 and have a tension arm such as 42 thereon supporting tension arm pulleys such as 48. Tension arm pulley 48 has a groove 50 therein and tension disc 44 has a groove 46 therein through which the yarn may be fed. A disc tensioner eyelet is provided as at 44' through which the yarn is initially fed. The yarn is designated generally as Y and after being fed around disc 44 and pulley 48, is fed around idler pulley 118 having groove 120 therein and supported by arm 116. Each strand of yarn (there are five shown in FIG. 1) is fed through detector heads such as 104, 106, 108, 110 and 112 located atop a flat portion 100 of member 34. Machine screws such as 102 secure the detector heads to portion 34. Each detector head has a groove such as 114 located therein which is generally called the yarn groove. A guide member 96 is provided atop section 38 and has a series of notches such as 98 therein through which each individual yarn is fed. A post 78 supports a journal 80 which, in turn, supports one end of a calibration shaft 82 having a series of calibration collars such as 84, 88, 90, 92 and 94 thereon. Each collar has a groove such as 86 located on collar 84.

A pair of nip rolls such as 70 are provided adjacent the calibration shaft. The other roller is not shown in FIG. 1. Roller 70 is downwardly biased by a spring (not shown) acting on level arms 68 and 76. A handle 74 is attached to a portion of the frame (not shown) and enables the user or operator to pull nip roll 70 of a similar underlying roll with which it is in contact. Machine screws such as 66 secure the arms 68 and 76 to the general framework of the apparatus.

Referring now to FIG. 2, there is shown a schematic diagram of the needle guide assembly, the solenoid assembly, and the adjustment assembly. The yarn, designated as Y, is fed over disc 40, over pulley 48, and pulley 118 into the yarn groove 114. Yarn groove 114 has a side wall 134 and it has a generally convex configuration. Detector head 104 has depending portions 130,132 which rest atop portion 100 of member 34. A slot 136 is located on the upper convex surface of yarn groove 114. In FIG. 2, the second nip roll is shown as 70, the first nip roll is shown supported by a shaft 72. Portion 138 has a bore therein which receives the end of an adjustment shaft 140 having a threaded portion 144 and a reduced diameter portion 142. A pointed adjustment screw 168 is mounted in portion 132 and looks into reduced diameter portion 142 to maintain shaft 140 in one longitudinal position. Provision is made for turning the shaft, as by slot 144, in the end thereof.

A plastic block 146 is mounted for transverse movement on threaded portion 144 of shaft 140. Block 146 is plastic and extends inwardly and has another bore receiving a smooth shaft (not shown) which extends between portions 130 and 132 of detector head 104. A bolt 148 secures an L-shaped contact member 148' and a lead terminal 152 to block 146. It should be noted at this time that block 146 is naturally insulated. A wire 154 extends from terminal 152 and is connected by a screw 160 to the plate member 156. Plate member 156 has a depending flange portion 158 which is biased against the top of adjustment screw 166 held in position by a lock nut 164 on member 162. Thus, with the use of biased flange 158, the detector head may be totally removed from the top portion 100 of member 34 without the necessity of unfastening any leads or connections.

Adapted to extend upwardly through slot 36 and head 104 is needle 170 which is held in a needle holder assembly 172 which has a slot 174 in an adjustment screw 176 which securely fastens the needle there within. Assembly 172 is mounted within a guide bushing assembly 178 supported by a bracket member 180. Assembly 172 is mounted within car 178 for vertical sliding movement.

Bracket 180 is supported on angle bracket 182 by machine screw 184 and is thus connected to support member 186 which in turn is held to angle bracket 182 by machine screw 188. Bracket 186 is supported on a base member 222 by machine screw 224. Angle bracket 182 supports a solenoid assembly 190 having a lower base portion 192, a cylindrical collar wall 192 and an inner collar wall 196. Located within the cylindrical chamber defined by wall 196 is a solenoid member 202 having a solenoid rod 200. Member 202 is normally biased downwardly by spring member 204 as shown in FIG. 2. Activation of solenoid 198 causes member 202 to move upwardly, as shown in FIG. 2, and rod 200 through coupling 206 moves upwardly as shown in FIG. 2, and rod 200 through coupling 206 moves perpendicularly to rod 208 upwardly therefrom.

A rod 218 extends down from assembly 172 to a yoke member 214. An adjustment nut 216 secures the rod in place and the distance between assembly 172 and yoke 214 may be adjusted by loosening nut 216 and adjusting rod 218. Yoke 214 is secured to cross member 208 by a collar 210 and travels downwardly therewith.

Referring now to FIGS. 3a, b and c, there is shown the electrical schematic of the control system designated generally as 300. A ll5-volt AC source is connected across terminals 301 and 302. To activate the system, the power ON switch 304 is depressed which activates power relay 307 to close power contacts 306 and 309. Light 308 also is lit to indicate the power is on. To turn the system off, the power OFF switch 305 is depressed which will deactivate relay 307 and its associate contacts. The overall system runs on AC power from the initial inputs of 301 and 302 and from the transformer 310. The counters 368, 381, 400, 414 and 428 are supplied power through a DC rectifier 365.

To calibrate the system, calibration button 312 is momentarily depressed. This activates calibration relays 316, 318 and 319 and ignites lamp 317. Calibration relay 316 closes contacts 376, 390 and 408 to activate solenoids 375, 389 and 409 respectively. Calibration relay 318 closes contacts 423 and 437 to solenoids 422 and 432, respectively. Relay 318 opens normally closed contacts 330 to remove the power from the run relay 323, and also closes contact 313 to keep the power to the calibration relays after the calibration switch has been released. Calibration relay 319 opens normally closed contact 350 to prevent time-out relay 352 from being activated and also closes contacts 358 to apply power to calibration motor 360. As will be explained later in the general functioning of the machine, the activated solenoids will insert the needle into the upright position and apply a given weight thereto for proper calibration of the indicating system. As long as the power is on, the contact sensors 377, 391, 410, 424 and 438 are activated as well as counters 368, 381, 400, 414 and 428. These counters and sensors are used during the calibration process. It should be noted that switch 312 is ganged by 314 to switch 326 in the laceup relay 321 power line.

After calibration, the lace-up button is depressed which opens ganged contact 315, closes contact 331 and opens contact 337. The opening of contact 315 deactivates the calibration relays 316, 318, 319 and extinguishes light 317. The opening of contact 337 prevents the application of power to run relay 323. The closing of contact 331 initiates lace-up relay 321 and ignites light 320. The activation of lace-up relay 321 closes contacts 332 to hold power thereto after the lace button is released.

The next operation is depressing the RUN button which closes the ganged contacts 329, opens contact 327, closes contact 333 and opens contact 361. Contact 329 connects the 24-volt DC source with the reset inputs 370, 383, 402, 416 and 431 of counters 368, 381, 400, 414 and 428 respectively. Contact 327 deactivates lace-up relay 321. Contact 333 applies power to run relay 323 and contact 361 resets timing circuit 364. Run relay 323 closes contacts 339 to keep power thereto upon the opening of contacts 333. Run relay 323 opens normally closed switch 340 to ignite stop-light 324 which has been ignited through the calibration and the lace-up. Run relay 325 is activated by the closing of contacts 442 by run relay 323. The run relays and their contacts will be opened or reset by the depression of stop button 334 or the opening of contacts 335 by the roll limit sensor. Also at the end of a 200 second cycle, timing circuit 365 will open normally closed contacts 338 to stop the run.

Run relay 325 controls the forward direction of nip roller drive motor 343. Upon activation of run relay 325, normally closed contacts 342 and 345 are open and contacts 344, 346 and 349 are closed. Thus, current will flow from power terminal 302 through closed contacts 344 to the lower right-hand corner of the drive motor, down through closed contacts 356 and 349 to the other power terminal 301.

Run relay 323 also closes contact 363 which initiates timing circuit 362. This timing circuit allows a 30 second time delay for the machinery to obtain its dynamic equilibrium before starting the sensing process. After 30 seconds, timing circuit 362 closes contact 365 of timing circuit 364 and contacts 351 to apply power down the line defined by points 355 and 396. It should be noted that 250 milliseconds after the power switch 304 was depressed, time delay relays 380, 394, 413, 427 and 441 close contacts 374, 385, 404, 418 and 433 in solenoid power circuits 375, 389, 409, 422 and 432 respectively. Thus when timing circuit 362 closes contacts 351, solenoids 37 5, 389, 409, 422 and 432 are activated. 200 seconds after the closing of contacts 265, timing circuit 364 opens normally closed contacts 338 to cut the power to run relay 323 which in turn cuts the power to run relay 325.

Upon deactivation of run relay 323, contacts 363 are opened and timing circuit 362 is deactivated. This opens contacts 351 which deactivates the solenoids and retracts the needles. While contacts 351 were closed, time-out relay 352 was activated which closed switch 357 to a second time-out relay 359 and opened normally closed contacts 348 in the drive motor 343s power circuit. The second time-out relay 359, when activated, closes contacts 347 also in the drive motor 343 s power circuit. Two seconds after the opening of contacts 351, the first time-out relay 352 closes normally closed contacts 348 and opens contacts 357. This allows nip roll drive motor 343 to reverse for the time of seven seconds which is determined by the second time-out relay 359. The reverse power circuit can be traced from power terminal 302 through now normally closed contacts 342 to the upper left side of the motor going through motor, coming out through now normally closed contacts 345 on the lower right-hand side and going through the closed circuit of closed contacts 347 and 348 to the other power terminal 301. The contacts 342, 344, 345 and 346 are in the state shown since run relay 325 is deactivated. in the 7 seconds after the opening of contact 357, time-out relay 359 is deactivated, opening switch 347 and shutting down the motor.

Of the five sensor circuits shown in FIGS. 3b and 30, only ones function will be disclosed. As indicated earlier, after the initial 30 seconds, contact 351 is closed applying power down 355 to normally closed contacts 373 and now closed contacts 374 to solenoid 375. When the needle detects a snag, contacts 378 are closed to activate contact sensor relay 377. Contact sensor relay 377 opens switch 373 to deactivate the solenoid and retract the needle and closes contact 371 which sends current through 372 to an event recorder. Relay 377 also opens relay 380. When time delay relay 380 is deactivated, contacts 443 assume their normally closed position to send a pulse to the counter and contacts 374 are opened to cut off the power to solenoid 375 and thus hold the needle retracted. When the needle is retracted, contacts 378 are opened, thus deactivating contact sensor relay 377. When contact sensor relay 377 is deactivated, contacts 373 and 397 assume their normally closed position. After 250 milliseconds, time delay relay 380 closes contacts 374 to reactivate solenoid 375 again.

The general operation of the electrical system is commenced by pressing the ON button. It lights and the five indicator lights accompanying each counter 20, 22, 28, 30 and 32 will momentarily light. The STOP button will also light. It is understood that each of the main control buttons has a light therein but it is not shown for purposes of clarity. The CAL button is then pressed and lights. The needle 170 then appears in slot 136 and yarn groove 114 and calibration shaft 192 will commence to rotate. The LACE button is then depressed causing the light to go off in the CAL button and the needle 170 will retract and shaft 92 will stop rotating. At this point, the nip roll is closed atop nip roll 70 and the RUN button is depressed, causing all the counters to reset to zero. The light will go off in the LACE and STOP buttons and the driven nip roll will start to rotate. After approximately 30 seconds, the needle points will again appear in the slot 136 through the action of timing circuit 362.

Depressing the STOP button will cause it to light and the light to go off in the RUN button and again the needle will retract and the nip rolls 70 and 70' will stop rotating. Time-out relay 352 causes a two second delay whereupon the rolls 70 and 70 will rotate in the reverse direction for 7 seconds under the control of relay 359. Pressing the RUN button after the 30 second delay period has passed allows one to open the nip rolls. Needle 170 will retract and the nip rolls 70 and 70' will stop. At this point, the OFF button should be pressed.

Operation of the tester is controlled from the master control display panel 5 by the lighted push buttons 6, 8, 10, 12, 14 and 16 with the sequence operations conforming to left to right orientation as viewed in FIG. 1. The counters 20, 26, 28, 30 and 32 display the sum of the number of yarn entanglements while the indicators below, such as 24, light simultaneously as each entanglement is counted. Each counter can be matched by color to a corresponding detector head, for instance, yellow or green, etc.

Yarn is drawn through the detector heads by the constant speed nip rolls 70 and 70 at the rate of l centimeter per second. Uniform tension of the yarn is constantly maintained at 100 grams by the pretensioners, such as 40, on the feed side of the machine. An entanglement is counted when it is strong enough to force needle 170 against contact 148' under detector head 104 and to thereby complete an electrically safe, resistive circuit. The force required to make such a contact is set and calibrated at 10 grams by adjusting the gap between needle 170 and the contact 148'. Timing of the length of the test for a 2 meter sample of yarn is maintained by automatically stopping the nip roll 70 and 70' at the completion of a 200 second-period from the beginning of the test period, this being determined by time circuit 364. The proper yarn tension and yarn rate of feed is obtained during the automatically controlled 30 second free test period as determined by time circuit 362. Interactions between entanglements are minimized and controlled by a regulated time delay relay set at 250 milliseconds delay from the time the initial contact is made until the needle is again in position to engage another entanglement, this being accomplished by counter delay 380. Thus, an entanglement will not be counted unless it is more than one twentyfifth millimeter from the previously counted entanglement. At the conclusion of the controlled test period, the nip rolls 70 and 70 are automatically reversed for seven seconds by relay 358 to remove the tension on the yarn, thus protecting needles 170 and tensioner 40 from accidental damage and/or unobserved shifts in calibration. Nip rolls 70 and 70 are also constructed with an interlock (not shown) that safely stops the machine and prevents damage to needle 170, the rolls are opened during a test run.

Operation for the yarn test on the machine consists primarily of lacing the yarn through the tester, running the test, recording the data, and preparing the next test. The total testing time for five simultaneous determinations can be less than 10 minutes.

A yarn entanglement is detected when it forces the needle 170 against contact 148' located under detector head 104. The force required to make this contact is set at 10 grams. This calibration is very critical. The contact is adjusted for the correct gap in force by rotating shaft 140, by inserting for example, a screw driver in slot 144. Clockwise adjustment of the screw portion 144 makes contact; counterclockwise adjustment breaks contact. When the adjustment is made, all the indicator lights at each counter position of the control display panel should be off. It they are not, the shaft 140 should be turned counterclockwise until the corresponding light does go off. The screw is then adjusted clockwise until the corresponding light on the control panel 5 for that detector position just turns on The screw direction is reversed just enough to turn the light off. Again the screw is turned clockwise until the corresponding light flickers, thus completing the calibration for that channel. These adjustments are made by placing a string with a weight suspended to the nip roll side into the groove 1 l4, groove 86 of rotating collar 84 opposite the corresponding detector head 104.

The disc tensioners, such as 40, are set and calibrated to maintain 100 grams tension on the yarn as it is pulled by nip rolls and 70'. The position of the tensioning arm pulley 48 can be adjusted by a mechanism not shown.

When a test is to be made, the nip rollers 70 and 70 are opened by pulling up on handle 74 and the LACE button should light up when depressed. The yarn from one bobbin, the creel, is then taken and the end lead is pushed through the disc tensioner eyelet 44 and around the tensioning disc 44 and under and over the tension arm pulley 48. The yarn is then placed into the groove of the detector head, which may have a Plexiglas cover thereon and then under the guide pulley immediately before the detector head, such as pulley 118. The yarn is then passed between the open nib rolls 70 and 70' and positioned in the appropriate notch, such as 98. At that point, the nip rolls are closed and the RUN button is pressed which causes the counters to reset to zero.

Thqtttaeh n w l run for. 3.0 sssot dsas 99229251 by relay 352, before the actual testing begins. This is to enable the operator to observe and make sure that all yarns are in the appropriate guides, rollers and grooves of each testing channel. It also insures that there will be no sagging filaments, particularly around the pretensioning areas and that the yarns fall freely off the nip rolls 70 and 70. At the conclusion of the 30 second period, the test will run for 200 seconds. After a momentary delay at the conclusion of the test, the nip rolls will reverse for approximately seven seconds as determined by relay 358 to remove the tension from the yarn.

At the conclusion of each run the data on the counters is recorded, the LACE button is depressed and the nip rolls opened. The yarns in the machine at that time are cut before the tensioner eyelets 44 and the yarn is pulled through the machine until the ends have cleared the nip rolls 70 and 70'.

With the instant machine, 50 bobbins per hour can be evaluated. Based on a texturing output of one doff/- hour/texturing machine, this unit has the potential to provide percent bobbin evaluation of 50 texturing machines.

The unit requires only one test operator. Virtually no operator variability can be introduced due to the automatic nature of the instrument. Yarn may be fed to the unit directly from packages mounted on a portable buggy. A small amount of twist introduced by pulling the yarn over the end of the package may be neglected.

The machine determines the rate of entanglement in five samples simultaneously and standardizes these determinations by eliminating from the operators control all variables that have an effect on the test results. This is accomplished in part by automatic regulation of the rate at which the yarn is fed through the instrument; an automatic pretesting period in which dynamic equilibrium is attained prior to entanglement counting; and an automatically controlled test period to provide accurate and precise lengths of samples.

While only one embodiment of this machine has been shown and described, it will be obvious to those of ordinary skill in the art that many modifications and changes can be made without departing from the scope of the appended claims.

What is claimed is:

l. A yarn entanglement detection apparatus comprising a support means, at least one yarn pretensioning means on said support means, roller means to pull yarn from said yarn pretensioning means, a detection head assembly, said assembly having a groove means through which yarn is adapted to be pulled and a needle means adapted to be selectively placed in said groove and in a retracted position, motor means to turn said roller means, a counter, and electrical circuit means associated with said needle means so as to control the position thereof, and said counter adapted to register each time said needle encounters an intermingling obstruction in a length of yarn being pulled through said apparatus, wherein said circuit means includes a first counter time delay means to retract said needle from said groove for a first small predetermined increment of time after each obstruction is encountered, said delay means cooperating with said circuit means to replace said needle in said groove after said first predetermined increment of time has expired and said circuit means also includes a second time delay relay means to maintain said needle in retracted position for a second predetermined interval of time after said roller means are activated and to then place said needle in said groove for a predetermined third interval of time.

2. An apparatus as in claim 1 wherein said circuit means also includes a third time delay relay means adapted to stop said roller means for a fourth predetermined interval of time after said third interval of time has expired and then to reverse the direction of rotation of said roller means fora fifth predetermined interval of time to allow said yarn to slacken.

3. An apparatus as in claim 2 wherein said first interval of time is about 250 milliseconds, said second interval of time is approximately 30 seconds, said third interval of time is approximately 200 seconds, said fourth interval of time is 2 seconds and said fifth interval of time is 7 seconds.

4. A yarn entanglement detection apparatus comprising a support means, at least one yarn pretensioning means on said support means, roller means to pull yarn from said yarn pretensioning means, a detection head assembly, said assembly having a groove means through which yarn is adapted to be pulled and a needle means adapted to be selectively placed in said groove and in a retracted position, motor means to turn said roller means, a counter, and electrical circuit means associated with said needle means so as to control the position thereof, and said counter adapted to register each time said needle encounters an intermingling obstruction in a length of yarn being pulled through said apparatus, said circuit means includes a laterally adjustable contact member spaced from said needle, said circuit means being operatively associated with said contact member and said needle means so that when said apparatus is activated and an entanglement forces said needle to engage said contact, it will register on said counter and said groove means includes an adjustment screw mounted thereunder, said contact member being mounted for movement toward and away from said needle upon rotation of said screw whereby the amount of force required to force said needle to engage said contact member is selectively adjustable by varying the distance therebetween.

5. An apparatus as in claim 4 and also including a shaft mounted on said support means having at least one collar with a groove therein, means to rotate said shaft whereby the test yarns with weights on one end thereof may be fixed at the opposite end, run through said groove means and over said collar in said groove to calibrate the amount of force needed to push said needle means against said contact member. 

1. A yarn entanglement detection apparatus comprising a support means, at least one yarn pretensioning means on said support means, roller means to pull yarn from said yarn pretensioning means, a detection head assembly, said assembly having a groove means through which yarn is adapted to be pulled and a needle means adapted to be selectively placed in said groove and in a retracted position, motor means to turn said roller means, a counter, and electrical circuit means associated with said needle means so as to control the position thereof, and said counter adapted to register each time said needle encounters an intermingling obstruction in a length of yarn being pulled through said apparatus, wherein said circuit means includes a first counter time delay means to retract said needle from said groove for a first small predetermined increment of time after each obstruction is encountered, said delay means cooperating with said circuit means to replace said needle in said groove after said first predetermined increment of time has expired and said circuit means also includes a second time delay relay means to maintain said needle in retracted position for a second predetermined interval of time after said roller means are activated and to then place said needle in said groove for a predetermined third interval of time.
 2. An apparatus as in claim 1 wherein said circuit means also includes a third time delay relay means adapted to stop said roller means for a fourth predetermined interval of time after said third interval of time has expired and then to reverse the direction of rotation of said roller means for a fifth predetermined interval of time to allow said yarn to slacken.
 3. An apparatus as in claim 2 wherein said first interval of time is about 250 milliseconds, said second interval of time is approximately 30 seconds, said third interval of time is approximately 200 seconds, said fourth interval of time is 2 seconds and said fifth interval of time is 7 seconds.
 4. A yarn entanglement detection apparatus comprising a support means, at least one yarn pretensioning means on said support means, roller means to pull yarn from said yarn pretensioning means, a detection head assembly, said assembly having a groove means through which yarn is adapted to be pulled and a needle means adapted to be selectively placed in said groove and iN a retracted position, motor means to turn said roller means, a counter, and electrical circuit means associated with said needle means so as to control the position thereof, and said counter adapted to register each time said needle encounters an intermingling obstruction in a length of yarn being pulled through said apparatus, said circuit means includes a laterally adjustable contact member spaced from said needle, said circuit means being operatively associated with said contact member and said needle means so that when said apparatus is activated and an entanglement forces said needle to engage said contact, it will register on said counter and said groove means includes an adjustment screw mounted thereunder, said contact member being mounted for movement toward and away from said needle upon rotation of said screw whereby the amount of force required to force said needle to engage said contact member is selectively adjustable by varying the distance therebetween.
 5. An apparatus as in claim 4 and also including a shaft mounted on said support means having at least one collar with a groove therein, means to rotate said shaft whereby the test yarns with weights on one end thereof may be fixed at the opposite end, run through said groove means and over said collar in said groove to calibrate the amount of force needed to push said needle means against said contact member. 